This invention relates to a vehicle suspension apparatus, the spring characteristic of which is switched over to a hard one when the cycle period of vertical vibration of the vehicle height is within a predetermined period of time.
An electronically controlled vehicle suspension apparatus has been proposed, in which the damping force of a shock absorber or spring constant of an air spring of a suspension unit for each wheel is electronically controlled to improve the comfortability of the passenger. In such an electronically controlled vehicle suspension apparatus, it is desired for the improvement of the comfortability that the characteristic of the suspension is automatically switched to a hard one to thereby reduce the vertical vibration of the vehicle height while the vehicle is running along a road having an irregular surface.